I would throw a combination of complex carbs and simple carbs in there. This is a time when your body can handle a signifcant amount of carbs and by combining the two simple and complex, you have some that are more rapidly digested and some that will take longer so you'll have a steady stream of glucose to
replenish muscle glycogen and signal insulin release. Keep fructose and fat to a minimum in the meal (shake). Depending on your size and goals, you could do something like 35gs of dextrose and 50gs of ground oats (just an example- and will depend on when you eat your next meal and what if anything you supplement with DURING your workouts).